A phased array, or electronically scanned array, is a controlled array of antennas that creates a beam of radio waves which can be electronically steered to point in different directions without moving the antennas. In an array antenna, the radio frequency current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction while cancelling to suppress radiation in undesired directions. Directional regions of high gain, referred to as “beams,” are formed by shifting the phase of the signal emitted from each radiating element to provide constructive and destructive interference to steer the beams in a desired direction. The relative amplitudes of the signals radiated by the individual antennas determine the effective radiation pattern of the array. A phased array may be used to point a fixed radiation pattern, or to scan rapidly in azimuth or elevation.